The present invention relates to a semiconductor package, and more particularly to a semiconductor package with a novel structure that prevents or reduces occurrence of warpage and solder ball defects due to thermal stress.
As is well known in the art, various techniques have been developed which allow the miniaturization, light-weight, high-speed operation and multi-functionality of electronic appliances. Semiconductor packages have thus been developed with the aim of reducing size and improving electrical characteristics. The ball grid array (BGA) package is a typical example.
The configuration of a conventional BGA package is as described below.
A semiconductor chip is attached to a substrate having circuit patterns. The bonding pads of the semiconductor chip and the electrode pads of the substrate are connected to each other by conductive bonding wires. A molding structure is formed on the upper surface of the substrate including the semiconductor chip and the bonding wires to protect the semiconductor chip and the bonding wires from external circumstances. Solder balls serving as mounting members for electrically connecting external circuits and the semiconductor chip to each other are formed on the lower surface of the substrate.
Since the BGA package has an overall size that is similar to the size of the semiconductor chip, the size of the mounting area is decreased. Further, because the BGA package is electrically connected to the external circuits through the solder balls, the minimization of electrical signal transmission paths improves the electrical characteristics.
However, in the conventional BGA package, since the molding structure is formed only on the upper surface of the substrate including the semiconductor chip and the bonding wires, the difference between the thermal expansion coefficients of the molding structure and the substrate causes warpage when heat is applied in subsequent processes and tests.
The warpage causes cracks in the connection portions of the solder balls and causes solder balls defects.